A United ireland is very probably desirable, although personally I dislike Nationalism as being the motivator.
It may even be an eventual unintended outcome of the vote to leave, dare I say it because of practicality more than ideology. However there is division in a significant part of the country which isn't simply going to melt away because of the consequence of the vote. A large part of my younger life was witnessing the troubles which were then improved by the GFA, which was something that tried to reconcile that division in a peaceful way.
For that reconciliation to be overtaken by the reality of the brexit vote implications it is not going to go down well, even if the aggrieved community largely voted leave.
Extreme Unionists would lobby for some kind of impractical hard border in Ireland before accepting a United Ireland.
Either way I don't believe leave voters could be bothered to consider the impact of their vote in Ireland, certainly those leading and influencing the leave campaign didn't mention it, it was all 350 million and Turkey.
So you may end up praising some kind of accident, but in the meantime there are the practical realities of two different systems on either side of something some consider to be a border to face.
At the moment we have the 'turn a blind eye' option heaving into view, but that is unsustainable in the long run.
Whatever else those who voted leave do not have a credible solution, until they do they might consider shutting the fuck up.